Functional sheet and lens using same

ABSTRACT

According to the present invention, a functional sheet, comprising a polarizing or photochromic functional layer and protective layers provided on both surfaces of the functional layer can be provided. The protective layers include an aromatic polycarbonate resin sheet or film. At least one of the protective layers is a co-extruded sheet or film including an aromatic polycarbonate resin layer and an acrylic-based resin layer provided on one surface or both surfaces of the aromatic polycarbonate resin layer. At least one surface of the functional sheet is of the acrylic-based resin layer. Also according to the present invention, a lens using such a functional sheet can be provided.

TECHNICAL FIELD

The present invention relates to a functional sheet having polarizationproperties or photochromic properties preferably usable for sunglasses,goggles, corrective lenses and the like, and a lens using such afunctional sheet.

BACKGROUND ART

Optical items such as sunglasses, goggles, and corrective lenses and thelike with polarizers are preferably used for the purpose of alleviatingthe glare provided by light reflected by a water surface, a snowsurface, a road surface or the like and making outdoor scenes easier tosee. When natural light is incident on, and reflected by, a watersurface or the like, there is a polarization component which ismonotonously increased with respect to the angle of reflection. Theabove-mentioned optical items utilize a phenomenon that when a polarizeris used such that an absorption axis thereof is horizontal, such apolarization component can be cut. Light can be described and behave bytwo straight polarizations perpendicular to each other. Therefore, wherea vibration component of light which is in a plane including theincident light and the normal direction thereto is p polarization, and acomponent vibrating in a plane perpendicular to the above-mentionedplane is s polarization, the p polarization of light reflected by awater surface or the like has a minimum point which becomes almost zeroat an angle of reflection of 55° or in the vicinity thereof, whereas thes polarization of such light monotonously increases. This s polarizationis cut.

There are also transparent optical items such as sunglasses, goggles,corrective lenses and the like including a layer containing aphotochromic colorant and thus having photochromic performance of beingcolored under external light containing a large amount of ultravioletrays and of being colorless under artificial light containing a smallamount of ultraviolet rays.

A known polarizer usable for these items is formed of a resin film,typically, a poly(vinyl alcohol) (PVA) film. Such a film is stretched inone direction while being dyed with iodine or a dichroic dye and thus isprovided with polarization properties.

Known methods for providing such a film with photochromic performanceinclude (1) a method of using a polymer solution containing aphotochromic colorant to form a casting film; (2) a method ofmelt-extruding a thermoplastic polymer containing a photochromiccolorant to form a film; (3) a method of preparing and using acomposition for forming a film, the composition containing aphotochromic colorant; (4) a method of preparing and using an adhesivecomposition containing a photochromic colorant; (5) a method ofthermally diffusing a photochromic colorant in a film or a substrate toform a photochromic diffusion layer; and the like (e.g., Patent Document1).

One method for applying any of the functional layers described above tooptical items such as sunglasses, goggles, corrective lenses and thelike uses a functional sheet including protective layers on bothsurfaces of a layer having polarization properties, a layer havingphotochromic properties, or a layer having both of these properties.

An example of a transparent plastic material usable for the protectivelayer is a thermoplastic resin. Examples of the thermoplastic resininclude aromatic polycarbonate, polymethylmethacrylate, transparentnylon, acetyl cellulose and the like.

Among these materials, aromatic polycarbonate is used from the viewpointof impact resistance. Polymethylmethacrylate, transparent nylon,hydrocarbon-based resins having an alicyclic substance as a main chain,acetyl cellulose and the like are used from the viewpoints of crackresistance, fashionability, and various other requirements.

A functional layer and a protective layer are integrated togetherusually by use of a curable resin adhesive, but troubles sometimes occurdue to adhesion failure between the functional layer and the protectivelayer.

Especially when aromatic polycarbonate is used for the protective layer,such an adhesion failure is often observed as delamination of thearomatic polycarbonate protective layer from the adhesive layer.

Aromatic polycarbonate has a problem of causing solvent cracks.Therefore, depending on the solvent used, an adhesive layer cannot beformed on the layer of aromatic polycarbonate, and moreover, theremaining solvent causes cracks. However, if excessive drying isperformed for the purpose of removing the solvent, the adhesive strengthis usually weakened. There are also limitations on forming an adhesivelayer on both adherend surfaces of aromatic polycarbonate for thepurpose of realizing strong adhesion.

In order to alleviate this problem, it is easily conceivable to form aprotective layer against the adhesive agent on an adhesive surface ofaromatic polycarbonate. In the case where the functional sheet includesa protective layer formed of aromatic polycarbonate, plasma treatment isperformed as a preparatory treatment for usual adhesion.

However, there is no document found yet which directly refers to forminga protective layer against the adhesive agent.

For other purposes, for example, for producing a thermosetting lensusing a functional sheet, there are methods by which a film resistantagainst a curable resin monomer solution is formed on a surface of afunctional sheet, for example, a film of a curable acrylic-based resinor the like is formed on a surface of a functional sheet (PatentDocuments 2 and 3).

An optical item such as sunglasses, goggles, corrective lenses or thelike using the above-mentioned functional sheet is usually produced asfollows. First, the functional sheet is molded to be a lens which iscurved as desired. Alternatively, the functional sheet is molded to be abent item having a curved surface, then the bent item is attached to amold, and a rear surface thereof is provided with a transparent plasticmaterial by means of injection molding, thereby forming a lens. The lensobtained by either method is subjected to hard-coating, reflectionprevention, and any other surface treatment when desired. Then, thesteps of shaping the lens to fit into the frame (external shapeprocessing), drilling holes, and tightening with screws, and the likeare conducted. In this manner, the optical item is assembled.

While being handled as described above, the layer of the transparentplastic material is exposed to stresses caused by abrasion, bending,compression, tension, twisting, non-uniform deformation due totemperature or humidity change, and the like. Among these, abrasion onthe surface layer of the transparent plastic material is a problem. Whenthe material is not highly resistant against abrasion, a product havingscratches is liable to be provided, which lowers the production yield.

Among the above-described functional sheets, a functional sheetincluding an aromatic polycarbonate layer, which is highly impactresistant, is easily scratched. Therefore, such a functional sheet is,for example, hard-coated after being produced (Patent Document 4).

Patent Document 5 describes that a protective layer formed of a(meth)acrylic-based resin may have an insufficient mechanical strengthor the like, and thus a polycarbonate-based resin layer is provided onan outer surface of a (meth)acrylic-based resin forming a protectivelayer so that the polycarbonate-based resin layer acts as an outersurface of the functional sheet.

CITATION LIST Patent Literature

Patent Document 1: Japanese Laid-Open Patent Publication No. H03-96901

Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-280154

Patent Document 3: Japanese Laid-Open Patent Publication No. 2005-305306

Patent Document 4: Japanese Laid-Open Patent Publication No. S61-032004

Patent Document 5: Japanese Laid-Open Patent Publication No. 2006-215465

SUMMARY OF INVENTION Technical Problem

Even a method by which the functional sheet, after being produced, ishard-coated is not considered to sufficiently prevent theabove-described problem, and scratches are generated at a certainprobability. In the case where post-treatment is necessary, materialsusable for the treatment need to be used. There are products providedwith no surface treatment such as hard-coating. In such a case, productswhich are less liable to be scratched are more preferable. Theinter-layer adhesive strength is considered to be improved by adding astep specifically provided for this purpose, but needless to say, it ismore preferable that the products are produced without such a step.

The present invention, made in light of such a situation, has an objectof providing a functional sheet including a polarizing or photochromicfunctional layer, having an improved adhesiveness between the functionallayer and a protective layer, and also having an improved resistance ofthe protective layer against abrasion; and a lens using such afunctional sheet.

Solution to Problem

Namely, the present invention is directed to the following.

(1) A functional sheet, comprising a polarizing or photochromicfunctional layer and protective layers provided on both surfaces of thefunctional layer, the protective layer including an aromaticpolycarbonate resin sheet or film; wherein at least one of theprotective layers is a co-extruded sheet or film including an aromaticpolycarbonate resin layer and an acrylic-based resin layer provided onone surface or both surfaces of the aromatic polycarbonate resin layer,and at least one surface of the functional sheet is of the acrylic-basedresin layer.

(2) The functional sheet according to (1) above, wherein the polarizingfunctional layer is produced by dyeing a poly(vinyl alcohol)-based resinfilm with a dichroic organic dye and stretching the poly(vinylalcohol)-based resin film.

(3) The functional sheet according to (1) above, wherein thephotochromic functional layer is produced by a casting method by use ofa non-aromatic-based polymer solution containing a photochromic organiccompound.

(4) The functional sheet according to (1) above, wherein thephotochromic functional layer is produced by heating and thus curing atwo-liquid thermosetting urethane resin containing a polyurethaneprepolymer which contains a photochromic organic compound and a curingagent.

(5) The functional sheet according to (4) above, wherein thephotochromic functional layer is a layer adhering to the co-extrudedsheet or film as the protective layer or adhering to the polarizingfunctional layer.

(6) The functional sheet according to (1) above, wherein theacrylic-based resin layer of the co-extruded sheet or film is a hardacrylic-based resin layer which exhibits a pencil hardness of 2H orhigher at a thickness of 60 pm, or a soft acrylic-based resin layercontaining, as a copolymerization component, 5 mol % or higher ofalkyl(meth)acrylate having an alkyl group with a carbon number of 2 orgreater.

(7) The functional sheet according to (1) above, wherein the co-extrudedsheet or film has a retardation of 3000 nm or greater.

(8) A lens obtained by a process by which the functional sheet accordingto (1) above which includes the acrylic-based resin layer at bothsurfaces thereof is subjected to external shape processing and subjectedto bending processing while being heated and pressurized.

(9) A molded lens obtained by a process by which the functional sheetaccording to (1) above, which includes the acrylic-based resin layer atone surface and the aromatic polycarbonate resin layer at the othersurface, is subjected to external shape processing such that theacrylic-based resin layer is on a convexed surface side, and issubjected to bending processing while being heated and pressurized; thenthe resultant sheet is attached to a mold such that the convexed surfaceside is in contact with the mold; and an aromatic polycarbonate resin isprovided on a concaved surface side of the sheet by injection molding.

(10) Sunglasses or goggles using the lens according to (8) or (9) above.

Advantageous Effects of Invention

Sunglasses, goggles and the like using a functional sheet according tothe present invention are improved in the production yield, and also areless liable to be scratched in use.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 provides schematic cross-sectional views each showing aco-extruded sheet usable as a protective layer according to the presentinvention.

FIG. 2 provides schematic cross-sectional views each showing afunctional sheet according to the present invention.

FIG. 3 provides schematic cross-sectional views each showing a bent lensusing a functional sheet according to the present invention.

FIG. 4 provides schematic cross-sectional views each showing a moldedlens using a functional sheet according to the present invention.

FIG. 5 is a schematic cross-sectional view showing a functional sheet inthe conventional art.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a functional sheet according to the present invention willbe described.

The functional sheet according to the present invention includes (a) apolarizing or photochromic functional layer; (b) protective layers atleast one of which is a co-extruded sheet or film of an aromaticpolycarbonate layer and an acrylic-based resin layer; and optionally (c)an adhesive layer for bonding the functional layer a and the protectivelayers b or bonding the functional layers a.

The present invention is also directed to a lens produced by performingbending processing on such a functional sheet; and a molded lensproduced by performing bending processing on such a functional sheet,attaching the resultant functional sheet to a mold, and providing thefunctional sheet with a transparent thermoplastic resin by means ofinjection molding.

[Polarizing Functional Layer]

A polarizing functional layer according to the present invention isusually produced by use of a poly(vinyl alcohol)-based resin film whichis dyed with a dichroic organic dye and stretched.

Examples of the poly(vinyl alcohol) include poly(vinyl alcohol) (PVA);poly(vinyl formal) which has trace amounts of acetic acid esterstructure of PVA, is a PVA derivative or is a PVA analog; poly(vinylacetal), saponified ethylene-vinyl acetate copolymer and the like. PVAis especially preferable. This film is stretched in one direction whilebeing immersed in, or caused to adsorb, a dichroic organic dye,optionally immobilized, and dried. Thus, a polarizing film is obtained.

The weight average molecular weight of the PVA film is 50,000 to350,000, preferably 150,000 to 300,000. The PVA film before beingdyed/stretched usually has a thickness of about 100 to 300 pm. The PVAfilm obtained as a result of stretching and dyeing usually has athickness of 10 to 50 μm.

The stretching magnification of the PVA film is 2 to 8 times, and isselected in accordance with the purpose. From the viewpoint of thepost-stretching strength, a preferable stretching magnification is 3 to5 times.

[Photochromic Functional Layer]

A photochromic functional layer according to the present invention isusable as (1) a photochromic film produced in advance or (2) aphotochromic adhesive layer containing a photochromic organic compound.

The (1) photochromic film includes a non-aromatic resin film and aphotochromic organic compound uniformly dispersed therein, and can beproduced by a known method such as a casting method, a melt extrusionmethod, a thermal diffusion method or the like. Resins usable for asubstrate include cellulose-based resins such as acetyl cellulose andthe like, saponified ethylene-vinyl acetate copolymer, and the like. Inthe case where the substrate film is required to have thermalresistance, for example, in the case where the photochromic film isproduced by a thermal diffusion method, a film of a curable substancesuch as polyurethane, diallylcarbonate or the like is usable.

In the case of (2) above, usually, any of substances usable for anadhesive layer described later is selected. Among such substances, asubstance which has a high photochromic response speed, is lessdeteriorated after long-time use, allows a desirable photochromicorganic compound to be uniformly mixed therewith in an amount as largeas possible, and is effective as an adhesive layer is selected.

According to the present invention, a two-liquid thermosetting urethaneresin containing a polyurethane prepolymer and a curing agent thereforis preferable.

Usable photochromic compounds include, for example, knownspiropyran-based, spirooxazine-based, and naphthopyran-based compounds.These compounds are used independently or in a combination of two ormore.

[Protective Layer]

According to the present invention, as at least one of the protectivelayers, a co-extruded sheet or film including an aromatic polycarbonateresin layer and an acrylic-based resin layer is used. The sheet or filmincluding an aromatic polycarbonate resin layer and an acrylic-basedresin layer may be produced by any of known methods such as an extrusionlamination method, a method of fusing the films or sheets by use of heator ultrasonic waves, a coating method and the like, instead of theco-extrusion method. Each method has advantages and disadvantages.

In the case of the extrusion lamination method, it specifically requiresa high level of skill to produce a thin acrylic-based resin which has ahigh surface hardness but is stable. The adhesive strength between thefilms obtained by the extrusion lamination method tends to be poor likethe adhesive strength between films or sheets fused by use of heat orultrasonic waves.

In the case of the coating method, when there is a solvent, a resinhaving a large molecular weight which cannot be extruded or the like isusable as a solution. A curable resin is also generally usable. As canbe seen, the coating method is a splendid method usable in a very widevariety of applications. However, an aromatic polycarbonate resin ispoor in the resistance against solvent cracks. Therefore, when anaromatic polycarbonate resin is used, it is indispensable to preciselycontrol the solvent to use, the components of the curable monomer andthe amount ratio thereof, the method of use and the like. There isanother problem that an aromatic polycarbonate resin film or sheethaving a high retardation value is inferior in the resistance againstsolvent cracks to an aromatic polycarbonate resin film or sheet having alow retardation value, and therefore requires more precise control.

According to the present invention, a co-extruded sheet or film whichhas no problem of the crack resistance and is obtained by mixing fusedresins in an extrusion die is used. Mixing fused resins in an extrusiondie is preferable in terms of the inter-layer adhesive strength and thestructure of the adhesion interface.

The co-extruded sheet or film according to the present invention is oftwo layers or three layers. The acrylic-based resin layer is selected asfollows. In the case of the two-layer film, an acrylic-based resin whichmainly fulfills the purpose of improving either the surface hardness orthe chemical resistance is usually selected. In the case of thethree-layer film, an acrylic-based resin which fulfills the purpose ofimproving both of the surface hardness and the chemical resistance isselected in addition to the above-selected acrylic-based resin.

Regarding specific uses, for a bent lens usable for sunglasses orgoggles, a sheet or film including an acrylic-based resin having a highsurface hardness at one surface is usually selected. For the surface incontact with the functional layer (i.e., for the inner surface), a layerwhich is soft and chemical-resistant is optionally selected, so thatthis surface can be used as a surface having an improved resistanceagainst organic solvents. Such a surface can improve the adhesivestrength at the interface and thus suppresses generation of a problem ofdelamination or the like.

In the case where the lens is subjected to bending processing, thenattached to a mold and subjected to injection molding so as to form amolded lens, the scratches or the like on the surface in contact withthe injection-molded resin (usually, the concaved surface) are usuallyerased by the melt resin. Usually, it is preferable that aromaticpolycarbonate is used for the surface layer from the viewpoint ofadhesiveness with aromatic polycarbonate used for injection molding. Theopposite surface of the functional sheet (usually, the convexed surface)is subjected to surface treatment, such as hard-coating, formation of areflection-preventive film or the like at the same time as the surfaceof the injection-molded aromatic polycarbonate resin of the molded lens(usually, the concaved surface). Therefore, it is preferable that theconditions for these steps are the same as much as possible for thesurface of the injection-molded resin and the opposite surface. Fromthis viewpoint, it is preferable that the opposite surface hassubstantially the same properties as those of the surface adhering tothe functional layer (inner surface). Since the opposite surface ispressed to the mold by the pressure of the resin during the injectionmolding and is also surface-treated, minute scratches or the like on theopposite surface are erased. For the surface adhering to the functionallayer (inner surface), a layer for improving the adhesive strength andsuppressing the generation of a problem such as delamination or the likeis preferably usable, like for the bent lens.

The protective layer has a thickness of 50 μm to 2 mm, preferably 100 μmor 1 mm.

In the case of the co-extruded sheet or film, the thickness of theacrylic-based resin layer is less than 50% of the total thickness, andis 10 μm or greater. Usually, the thickness of the acrylic-based resinlayer is selected from 10 μm to 500 μm, preferably from 20 to 100 μm.

The retardation value of the co-extruded sheet or film is selected fromthe range of 100 nm or less, or 3000 nm or greater.

In the case where the retardation value is 100 nm or less, it ispreferable to use a copolymeric polycarbonate resin produced bycopolymerizing monomers each containing an aromatic ring directedperpendicular to the main chain (e.g., fluorene group-substitutedbisphenol, styrene graft bisphenol A polycarbonate, etc.) so that thephotoelasticity is decreased.

In the case of a normal aromatic polycarbonate resin (using2,2-bis(4-hydroxyphenyl)propane), a film or sheet having a retardationvalue of 3000 nm or greater and 20000 nm or less, preferably 4000 nm orgreater, especially preferably 5000 nm or greater, is selected. A highretardation value means a large stress (residual stress) due tomolecular alignment. In general, a film or sheet of aromaticpolycarbonate resin having a high retardation value also has adisadvantage of being inferior in the crack resistance to a film orsheet having a small residual stress.

A conventional sheet or film formed only of an aromatic polycarbonateresin having a high retardation value of 3000 nm or greater is producedby the following method. The aromatic polycarbonate resin of atemperature higher than the glass transition temperature is delaminatedfrom the roll, and the resin is stretched and cooled, so that the amountof stretching is controlled.

A co-extruded sheet or film having an improved surface hardness used inthe present invention and having a high retardation value is notindustrially produced.

The above-described method used for the aromatic polycarbonate resin wasapplied to the co-extruded sheet or film having an improved surfacehardness as it was. When the amount of stretching was increased, thefilm was disrupted and was not produced successfully.

By contrast, when the co-extruded sheet or film is stretched by abatch-system stretch machine while being heated, a sheet or film havinga high retardation value can be produced. Based upon this, it isconsidered that the film is disrupted because the acrylic-based resinlayer on the surface is cracked and thus is disrupted. Therefore, it isestimated that if, for example, the acrylic-based resin layer side ofthe co-extruded sheet or film in an area to be delaminated from the rolland stretched is kept at a temperature no more than the glass transitiontemperature of the aromatic polycarbonate resin and no less than theglass transition temperature of the acrylic-based resin and thus adefect (cracks, etc.)

of the acrylic-based resin layer is prevented, a sheet or film having alarge amount of stretching (having a high retardation value) can beproduced. It is also estimated that when a flexible copolymercontaining, for example, 10 mol % or higher of an acrylic-based resinhaving a large carbon number of ester group is used as acopolymerization component, a large amount of stretching can be achievedmore easily although such a copolymer is inferior in terms of theimprovement degree of the surface hardness or crack resistance whenthere is no defect.

An aromatic polycarbonate resin usable for the present invention is apolymer produced from a well-known method from, for example, a monomersuch as a bisphenol compound represented bybishydroxy(halogeno)phenylalkane such as2,2-bis(4-hydroxyphenyl)propane,2,2-bis(4-hydroxy-3,5-dibutylphenyl)propane or the like, or a monomer inwhich the alkane part is substituted with a fluorene group or the like.

The molecular weight may be in a usual range, and is preferably 17,000to 40,000 by the viscosity average molecular weight from the viewpointof ease of shaping and mechanical strength, and is more preferably20,000 to 30,000 from the viewpoint of ease of production by extrusion.

An acrylic-based resin usable for the present invention may be a singlepolymer of any of various (meth)acrylic acid esters represented bypolymethylmethacrylate (PMMA) and polymethacrylate (PMA), a copolymer ofmethylmethacrylate (MMA) or methylacrylate (MA) and at least one othermonomer, or a mixture of a plurality of such resins.

A hard acrylic-based resin usually having a hardness of 2H containingMMA or MA as a main component is preferably used for a surface layer forthe purpose of resisting against abrasion. By contrast, a copolymer ofalkyl(meth)acrylate having an alkyl group with carbon number of 2 orgreater, more specifically, a soft acrylic-based resin usuallycontaining 5 mol % or higher of, preferably 10 mol % or higher of, suchalkyl(meth)acrylate, is flexible and has a high adhesiveness althoughbeing inferior in terms of the improvement degree of the surfacehardness or crack resistance. Therefore, such a copolymer is preferablyused for an inner surface or a surface of a pre-treatment layer forcoating such as hard-coating or the like.

Other monomers copolymerizable with MMA or MA includealkyl(meth)acrylate having a carbon number of alkyl group of 2 to 18;α,β-unsaturated acid such as acrylic acid, methacrylic acid or the like;bivalent carboxylic acid containing unsaturated group such as maleicacid, fumaric acid, itaconic acid or the like; alkylesters thereof;aromatic vinyl compounds such as styrene, a-methylstyrene,nucleus-substituted styrene and the like; vinyl cyanide compounds suchas acrylonitrile, methacrylonitrile and the like; maleic acid anhydride,maleimide, N-substituted maleimide; and the like. Usable monomersfurther include mixtures of copolymers thereof and various derivativesthereof such as hydrogen-added substances and the like. Among these,aliphatic compounds are preferable. Alkyl(meth)acrylate having a carbonnumber of alkyl group of 2 to 18 is preferable. In addition, a substanceobtained by adding hydrogen to a benzene ring of an acrylic-based resinobtained by copolymerization of styrene or the like is usable. Examplesof such (meth)acrylic-based resins include Acrypet (trademark; producedby Mitsubishi Rayon Co., Ltd.), Delpet (trademark; produced by AsahiKasei Chemicals Corporation), Parapet (trademark; produced by KurarayCo., Ltd.), and the like.

[Adhesive Layer]

According to the present invention, an adhesive layer is used forbonding a protective layer and a functional layer, and in the case wherea polarizing film layer and a photochromic film are used as functionallayers, the adhesive layer is used for bonding the functional layers.

Usable adhesives include acrylic resin-based materials, urethaneresin-based materials, polyester resin-based materials, melamineresin-based materials, epoxy resin-based materials, silicone resin-basedmaterials, and the like. Specifically from the viewpoint of adhesivenesswith aromatic polycarbonate, and adhesiveness with the polarizing layeror the photochromic layer, a two-liquid thermosetting urethane resincontaining a polyurethane prepolymer, which is an urethane resin-basedmaterial, and a curing agent is preferable.

[Production of the Functional Sheet]

A functional sheet according to the present invention is produced by useof the above elements.

Usually, a co-extruded sheet or film including an aromatic polycarbonateresin layer and an acrylic-based resin layer used as protective layersof the present invention is available in the form of a lengthy roll andthus is used in this form. A polarizing functional layer is alsoavailable in the form of a lengthy roll and thus is used in this form.In the case where a photochromic film produced as a photochromicfunctional layer is used, such a photochromic film is available in theform of a lengthy roll and thus is used in this form. A sheet or filmdrawn out of each of the rolls is subjected to prescribed surfacetreatment as necessary, and then a solution of an adhesive according tothe present invention is applied thereto. Each of the resultant sheetsor films is dried to form an adhesive layer substantially with nosolvent. These sheets or films are laminated and bonded together bypressurization. Then, the resultant sheet or film is taken into a roll,or cut into a prescribed size. The resultant sheet or film is stored sothat the curing reaction proceeds. Thus, the functional sheet isproduced.

In the case where the photochromic functional layer is formed of anadhesive composition, the functional layer is usually formed insubstantially the same manner as described above except that a thickadhesive layer is formed.

First, in the case where only the photochromic functional layer isincluded, namely, a polarizing film is not used, the photochromicfunctional layer needs to be formed on a surface of the co-extrudedsheet or film. Therefore, a substance which is not harmful for aromaticpolycarbonate is selected as a component of a photochromic adhesivecomposition, or a layer providing a solvent resistance is used. As thelayer providing a solvent resistance, the acrylic-based resin layer sideof the co-extruded sheet or film including the above-mentioned softacrylic resin layer is used, for example.

In the case where a polarizing film is used, the functional sheet isproduced as follows. An adhesive composition layer is formed on onesurface of the polarizing film, and the polarizing film is bonded to theco-extruded sheet or film. Then, a photochromic adhesive compositionlayer with no solvent is formed on the opposite surface of thepolarizing film, and the aromatic polycarbonate of the co-extruded sheetor film is laminated on the photochromic adhesive composition layer.Alternatively, as described above, as the co-extruded sheet or filmaccording to the present invention, a sheet or film including a flexibleacrylic copolymer layer is used.

In the case where a polarizing film is used and a protective sheet orfilm having a high retardation value is adopted, great care is neededbecause such a sheet or film having a high retardation value tends to beinferior in the crack resistance to a sheet or film having a lowretardation value. In the case where a sheet or film having a highretardation value is used, the stretching direction of the sheet or filmand the stretching direction of the polarizing film are parallel to eachother or perpendicular to each other.

[Production of the Lens]

The polarizing functional sheet, the photochromic functional sheet, orthe polarizing and photochromic functional sheet produced above is usedto form a lens. The functional sheet is subjected to external shapeprocessing such that the acrylic-based resin layer is at the convexedsurface, and then is subjected to bending processing while being heatedand pressurized. Thus, a processed lens is produced. Alternatively, thefunctional film which has been subjected to external shape processingand bending processing in the same manner as described above is attachedto a mold such that the convexed surface is in contact with the mold,and is provided with a transparent thermoplastic resin on the concavedsurface by means of injection molding. Thus, a molded lens is produced.

In the case where the bent lens is used without injection molding, it isnecessary that the lens itself has a strength. Both surfaces of the lensare surfaces of the lens as the final product. Therefore, a functionalsheet including a thick protective layer and is structured such thatboth surfaces are of an acrylic-based resin is selected. The totalthickness of the functional sheet including the two acrylic-based resinlayers is 0.8 mm or greater, preferably 1 to 3 mm. In the case of aco-extruded sheet using usual aromatic polycarbonate, it is preferablethat the retardation value is high.

In the case where the molded lens is produced by means of injectionmolding, a fused resin is provided on the surface of the functionalsheet to which injection molding has been performed. Therefore, defectsother than foreign objects, for example, defects like scratches or thelike are erased. In consideration of this and also the adhesiveness witharomatic polycarbonate usually used for injection molding and opticalproperties, it is preferable that the surface of the functional sheet isof aromatic polycarbonate. The thickness of the protective layer on theside to which injection molding is performed merely needs to besufficient to protect the functional layer.

The surface of the functional sheet in contact with the mold, which isusually the convexed surface, usually has various functional layersformed thereon after the molded lens is produced. For this reason, forthe protective layer on this side, a substance which is suitable to suchsurface treatment steps is preferable. For example, a flexible acryliccopolymer layer is used as the protective layer on the side of the mold.

The total thickness of the functional sheet including the two protectivelayers is 0.3 mm or greater, preferably 0.4 to 0.9 mm.

According to the present invention, in the case where a functional sheetincluding a polarizing layer is selected and a co-extruded sheet usingusual aromatic polycarbonate is selected as described above, it ispreferable that the co-extruded sheet has a high retardation value.

A most general usual aromatic polycarbonate resin, namely, apolycarbonate resin containing 2,2-bis(4-hydroxyphenyl)propane as a mainmonomer has a large optical elasticity constant.

Therefore, when this polycarbonate resin having such a large opticalelasticity constant is used, unless any special operation of keeping theretardation value low is used, stress caused by fixing the lens to theframe or a temperature change or stress caused by bending processing orthe like remains. In a functional sheet including a polarizing layer,interference fringes are observed due to birefringence generated by thestress.

By contrast, when a co-extruded sheet having a sufficiently largeretardation value is used, such stress does not cause new interferencefringes. A reason for this is that with a co-extruded sheet having asufficiently large retardation value, the change due to the value ofstress birefringence is negligible, and therefore the direction thereofis not substantially changed.

Hereto, schematic cross-sectional views showing a co-extruded sheet usedas a protective layer according to the present invention describedabove, schematic cross-sectional views showing a functional sheet,schematic cross-sectional views showing a bent lens and a molded lenseach using the functional sheet, and a schematic cross-sectional viewshowing a functional sheet in the conventional art are attached.

FIG. 1 provides schematic cross-sectional views each showing aco-extruded sheet used as a protective layer according to the presentinvention. The thickness of each layer or the like is optionallychangeable, but there are four layer structures shown here for theco-extruded sheet. Reference sign 2 refers to a hard acrylic-based resinlayer, and is provided mainly for improving the surface hardness.Reference sign 3 refers to a soft acrylic-based resin layer, and isprovided mainly for improving the solvent resistance and the inter-layeradhesiveness.

FIG. 2 provides schematic cross-sectional views each showing afunctional sheet according to the present invention corresponding toeach of the examples. FIG. 2 a and FIG. 2 b correspond to Examples 1 and2, respectively. The functional sheet includes the hard acrylic-basedresin layer 2 at both surfaces thereof. In FIG. 2 b, the softacrylic-based resin layers 3 are included on the inner side. FIGS. 2 c,2 d and 2 e correspond to Examples 3, 4 and 5, respectively. Thefunctional sheet includes the aromatic polycarbonate resin layer 1 atone surface thereof In FIG. 2 d, the soft acrylic-based resin layers 3are included at the inner side.

The functional sheet according to the present invention includes thehard or soft acrylic-based resin layer 2 or 3 at at least one surfacethereof The soft acrylic-based resin layer is superior in the abrasionresistance to the aromatic polycarbonate resin layer 1. The surfacehaving the soft acrylic-based resin layers 3 has an improvedadhesiveness. The aromatic polycarbonate resin layer 1 is provided onone surface in order to be integrated with the aromatic polycarbonateresin layer 7 provided by injection molding and thus is formed into amolded product with no interface.

FIG. 3 provides schematic cross-sectional views each showing a bent lens(Example 6) using the functional sheet according to the presentinvention corresponding to each of Examples 1 and 2. These lenses areobtained by bending processing performed on the functional sheets inFIGS. 2 a and 2 b. The lenses each have the hard acrylic-based resinlayer 2 at both surfaces thereof and thus have an improved abrasionresistance.

FIG. 4 provides schematic cross-sectional views each showing a moldedlens (Example 7) using the functional sheet according to the presentinvention corresponding to each of Examples 3, 4 and 5.

FIG. 5 is a schematic cross-sectional view showing a functional sheet inthe conventional art.

The lenses produced above were used as they were, or were optionallyprovided with any of various functional layers such as areflection-preventive layer, a hard-coating layer, a stain-preventivelayer, an anti-fogging layer and the like. Alternatively, the lenses areprovided with gradations or other designs by dyeing or the like, and arepreferably used for sunglasses, goggles, corrective glasses or the like.

The functional sheet according to the present invention may be used fora polarizing plate, a photochromic plate, a polarizing/photochromicplate or the like as it is as a sheet having an improved abrasionresistance, or after being optionally provided with any of variousfunctional layers such as a reflection-preventive layer, a hard-coatinglayer, a stain-preventive layer, an anti-fogging layer and the like.

EXAMPLES

Hereinafter, the present invention will be described by way of examples.

[Protective Layer]

Co-Extruded Sheet 1 (see FIG. 1 a):

A PC/PMMA co-extruded sheet (PMMA: methylmethacrylate; produced byMitsubishi Gas Chemical Company Inc.) was stretched while being heatedat a temperature of 160° C. by a batch-system stretch machine to have athickness of 0.7 mm (thickness of the PMMA layer: 100 μm) and aretardation value of about 5500 nm.

This sheet has an inclination structure occurring at an interfacebetween PC and PMMA, and the interface has a relatively low lightreflectance.

Co-Extruded Sheet 2 (see FIG. 1 b):

A PMMA/PC/C-PMMA co-extruded sheet (C-PMMA: a copolymer ofmethylmethacrylate, methylacrylate and butylacrylate; produced byMitsubishi Gas Chemical Company Inc.) was monoaxially stretched asdescribed above to have a thickness of 0.7 mm and a retardation value ofabout 5500 nm (thickness of the PMMA layer: 100 μm; thickness of theC-PMMA layer: about 30 μm).

This sheet also has an inclination structure occurring at the interfacesas described above.

Co-Extruded Sheet 3 (see FIG. 1 a):

A PC/PMMA two-layer co-extruded sheet having a thickness of 0.3 mm(thickness of the PMMA layer: 60 μm; produced by Mitsubishi Gas ChemicalCompany Inc.) was prepared. This sheet has an inclination structureoccurring at the interface as described above.

Co-Extruded Sheet 4 (see FIG. 1 a):

A PC/PMMA two-layer co-extruded sheet produced by Mitsubishi GasChemical Company Inc.) was monoaxially stretched as described above tohave a thickness of 0.3 mm and a retardation value of about 5500 nm(PMMA: a copolymer of methylmethacrylate and methylacrylate; thickness:about 50 μm).

This sheet also has an inclination structure occurring at the interfaceas described above.

Co-Extruded Sheet 5 (see FIG. 1 c):

A C-PMMA/PC/C-PMMA three-layer co-extruded sheet (produced by MitsubishiGas Chemical Company Inc.) was monoaxially stretched as described aboveto have a thickness of 0.3 mm and a retardation value of about 5500 nm(thickness of the C-PMMA layer: about 30 μm).

This sheet also has an inclination structure occurring at the interfacesas described above.

Co-Extruded Sheet 6 (see FIG. 1 d):

A PC/C-PMMA co-extruded sheet (produced by Mitsubishi Gas ChemicalCompany Inc.) was monoaxially stretched as described above to have athickness of 0.3 mm and a retardation value of about 5500 nm (thicknessof the C-PMMA layer: about 30 μm).

This sheet also has an inclination structure occurring at the interfaceas described above.

Separately from the above, a usual sheet of bisphenol A polycarbonate(PC) having a thickness of 0.3 mm, and PC sheets having a thickness of0.3 mm and 0.7 mm and having a retardation value of about 5500 nm wereprepared.

[Polarizing Film (Polarizing Layer)]

A PVA film (trade name: VF-PS#7500 produced by Kuraray Co., Ltd.) wasimmersed in water of 35° C. to remove glycerin from the film. Next, theresultant film was immersed in an aqueous solution of 35° C. containing35 g/L of Sumilight Red 4B-P (C.I. 28160), 0.18 g/L of Chrysophenine(C.I. 24895), 1.33 g/L of Sumilight Supra Blue G (C.I. 34200), and 5 g/Lof anhydrous sodium sulfate for 3 minutes. During and after this dyeingprocess, the film was monoaxially stretched to be four times larger. Theresultant dyed film was immersed in an aqueous solution of 35° C.containing 2.5 g/L of nickel acetate and 6.0 g/L of boric acid for 3minutes. The resultant film was dried at room temperature for 3 minutesin the state where the tensile state was maintained, and then heated at110° C. for 3 minutes. Thus, a polarizing film was obtained.

[Photochromic Adhesive Solution]

To 100 g of polyurethane prepolymer, 20 g of curing agent was added. Tothe resultant substance, 0.82 g (1% with respect to the total amountafter volatization of the solvent and curing) of4-[4-[6-(4-morphonyl)-3-phenyl-3H-naphtho(2,1-b)pyran-3-yl]phenyl]-morphine(trade name: Reversacol Flame, produced by James Robinson, Ltd.) wasadded as a photochromic compound, and stirred at room temperature for 1hour. Thus, a photochromic adhesive solution was prepared.

[Adhesive Composition]

To 50 parts by weight of polyurethane prepolymer, 5 parts by weight ofcuring agent and 60 parts by weight of ethyl acetate as a solvent wereadded. Thus, an adhesive composition was prepared.

Example 1 (see FIG. 2 a)

To one surface of the polarizing film obtained above, the adhesivecomposition was applied by use of a coater and dried at 110° C. for 5minutes. The two-layer co-extruded sheet 1 having a thickness of 0.7 mmwas laminated thereon such that the PC layer would be in contact withthe adhesive composition. Next, on the surface of the polarizing film ofthe resultant laminate, an adhesive layer was formed in the same manner.Then, another co-extruded sheet 1 was laminated such that the PC layerwould be in contact with the adhesive layer. The resultant laminate wasdried at room temperature for 1 day or longer and then at 70° C. for 1day. Thus, a polarizing sheet of PMMA*PC/adhesive layer/polarizingfilm/adhesive layer/PC*PMMA having a thickness of 1.5 mm was obtained.Both of the surfaces of the polarizing film were of PMMA.

The resultant polarizing sheet was subjected to a pencil hardness test(JIS-K-5600-5-4). The polarizing sheet was confirmed to have a pencilhardness of 3H.

Comparative Example 1 (see FIG. 5)

A polarizing sheet of PC/adhesive layer/polarizing film/adhesivelayer/PC was obtained in the same manner as in Example 1 except that theabove-described polycarbonate sheet having a high retardation (producedby Mitsubishi Gas Chemical Company Inc.) was used instead of theco-extruded sheet 1 used in Example 1.

The resultant polarizing sheet was subjected to a pencil hardness testin the same manner as in Example 1. The polarizing sheet had a pencilhardness of B.

Example 2 (see FIG. 2 b)

To the C-PMMA-side surface of the three-layer co-extruded sheet 2 havinga thickness of 0.7 mm, the above-described adhesive composition wasapplied by use of a coater and dried at 110° C. for 5 minutes. Then, theabove-obtained polarizing film was laminated thereon by use of alaminator. Separately, on the co-extruded sheet 2, the adhesivecomposition was applied thereto and dried in the same manner asdescribed above. On the surface of the polarizing film of theabove-obtained laminate, the separately obtained sheet was laminatedsuch that the C-PMMA-side surface thereof would be in contact withpolarizing film. Next, the resultant laminate was dried at roomtemperature for 1 day or longer and then at 70° C. for 1 day. Thus, apolarizing sheet of PMMA*PC*C-PMMA/adhesive layer/polarizingfilm/adhesive layer/C-PMMA*PC*PMMA having a thickness of 1.5 mm wasobtained. Both of the surfaces of the polarizing sheet were of PMMA.

The resultant polarizing sheet was subjected to a pencil hardness testin the same manner as in Example 1. The polarizing sheet was confirmedto have a pencil hardness of 3H.

In the case where the adhesive composition is applied to the PC-sidesurface and dried, minute cracks are often observed. In this example, nominute crack was observed.

Example 3 (see FIG. 2 c)

A polarizing sheet of PMMA*PC/adhesive layer/polarizing film/adhesivelayer/PC having a thickness of 0.6 mm was obtained in the same manner asin Example 1 except that the co-extruded sheet 4 (2) having a thicknessof 0.3 mm was used as one protective sheet and a high retardation PCfilm having a thickness of 0.3 mm was used as the other protectivesheet, instead of the co-extruded sheet 1 used in Example 1.

The resultant polarizing sheet was subjected to a pencil hardness testin the same manner as in Example 1. The polarizing sheet had a pencilhardness of 3H on the PMMA side and a pencil hardness of B on the PCside.

Example 4 (see FIG. 2 d)

To the C-PMMA-side surface of the three-layer co-extruded sheet 5 havinga thickness of 0.3 mm, the above-described adhesive composition wasapplied by use of a coater and dried at 110° C. for 5 minutes. Then, theabove-obtained polarizing film was laminated thereon by use of alaminator. Separately, on the C-PMMA-side surface of the two-layerco-extruded sheet 6 having a thickness of 0.3 mm, the adhesivecomposition was applied thereto and dried in the same manner asdescribed above. On the surface of the polarizing film of theabove-obtained laminate, the separately obtained sheet was laminatedsuch that the C-PMMA-side surface thereof would be in contact withpolarizing film. Next, the resultant laminate was dried at roomtemperature for 1 day or longer and then at 70° C. for 1 day. Thus, apolarizing sheet of C-PMMA*PC*C-PMMA/adhesive layer/polarizingfilm/adhesive layer/C-PMMA*PC* having a thickness of 0.6 mm wasobtained.

The resultant polarizing sheet was subjected to a pencil hardness testin the same manner as in Example 1. The resultant polarizing sheet had apencil hardness of H on the C-PMMA side and a pencil hardness of B onthe PC side.

In the case where the adhesive composition is applied to the PC-sidesurface and dried, minute cracks are often observed. In this example, nominute crack was observed, like in Example 2.

Example 5 (see FIG. 2 e)

The above-obtained photochromic adhesive solution was applied to theco-extruded sheet 3 by use of a coater and dried at 70° C. for 10minutes. Then, on the resultant sheet, a usual PC film was laminated byuse of a laminator. Next, the resultant laminate was dried at roomtemperature for 1 day or longer and then at 70° C. for 1 day to becured. Thus, a photochromic sheet of PMMA*PC/photochromic layer/PC wasobtained.

The resultant photochromic sheet was subjected to a pencil hardness testin the same manner as in Example 1. The photochromic sheet had a pencilhardness of 3H on the PMMA side and a pencil hardness of B on the PCside.

Example 6 (see FIG. 3)

The polarizing sheets of Examples 1 and 2 each having a thickness of 1.5mm were punched into a rectangular capsule shape having a length of 80mm in the stretching direction and a width of 55 mm in a directionperpendicular thereto, with the four corners thereof being cut away.

Each of these capsule-shaped pieces was subjected to bending processingas follows. A concaved spherical bending mold (radius of curvature:66.81 mm; base curve: 7.932) coated with a silicone rubber sheet andhaving a function of vacuum absorption was used. Each capsule-shapedpiece was placed on a female silicone rubber sheet which was set to asurface temperature of 145° C., and vacuum absorption was started. Next,the capsule-shaped piece was pressurized with a male spherical bent moldcoated with a silicone rubber sheet. Thus, the capsule-shaped piece wasformed into a spherical shape. Herein, the “base curve” is a curvatureof a front surface of the lens, and is a value obtained by dividing 530by the radius of curvature in units of millimeters.

The steps of punching and bending the sheet into a desired shape wereconducted successfully, and lenses having a surface which is not liableto be scratched were obtained.

Example 7 (see FIG. 4)

The polarizing sheets of Examples 3 and 4 each having a thickness of 0.6mm and the photochromic sheet of Example 5 having a thickness of 0.6 mmwere each punched into a true circular shape having a diameter of 79.5mm and cut to have a width in a direction perpendicular to thestretching direction of 55 mm.

Next, each of these pieces was subjected to bending processing so as tohave a shape matching a spherical surface (radius of curvature: 66.81mm; base curve: 7.932) of a mold used for injection molding. The bendingprocessing was performed by use of a mold having the same surface shapeas that of the mold used for injection molding, in the state where thePMMA- or C-PMMA-side was on the convexed surface side.

The bent pieces were each inserted into the mold to be used for theinjection molding, and was provided with an aromatic polycarbonate resinon the concaved surface side by injection molding performed at 300° C.Thus, aromatic polycarbonate polarizing and photochromic lenses wereproduced.

The resultant molded lenses are usually used after being, for example,hard-coated. Even without being hard-coated, the convexed surface ofthese lenses is not liable to be scratched. Therefore, these lenses areeasy to be handled, and are also improved in the post-hard-coatingabrasion resistance.

INDUSTRIAL APPLICABILITY

A functional sheet and a lens using the same according to the presentinvention provide a stable inter-layer adhesive strength and a superbabrasion resistance, and are highly applicable to post-processing suchas hard-coating, and thus are preferably usable for sunglasses, goggles,corrective glasses or the like.

REFERENCE SIGNS LIST

-   1 Aromatic polycarbonate resin layer-   2 Hard acrylic-based resin layer-   3 Soft acrylic-based resin layer-   4 Adhesive layer-   5 Polarizing film layer-   6 Photochromic film layer-   7 Aromatic polycarbonate resin layer obtained as a result of    injection molding

1. A functional sheet, comprising a polarizing or photochromicfunctional layer and protective layers provided on both surfaces of thefunctional layer, the protective layers comprising an aromaticpolycarbonate resin sheet or film; wherein at least one of theprotective layers is a co-extruded sheet or film comprising an aromaticpolycarbonate resin layer and an acrylic-based resin layer provided onone surface or both surfaces of the aromatic polycarbonate resin layer,and at least one surface of the functional sheet is of the acrylic-basedresin layer.
 2. The functional sheet according to claim 1, wherein thepolarizing functional layer is produced by dyeing a poly(vinylalcohol)-based resin film with a dichroic organic dye and stretching thepoly(vinyl alcohol)-based resin film.
 3. The functional sheet accordingto claim 1, wherein the photochromic functional layer is produced by acasting method by use of a non-aromatic-based polymer solutioncomprising a photochromic organic compound.
 4. The functional sheetaccording to claim 1, wherein the photochromic functional layer isproduced by heating and thus curing a two-liquid thermosetting urethaneresin comprising a polyurethane prepolymer which comprises aphotochromic organic compound and a curing agent.
 5. The functionalsheet according to claim 4, wherein the photochromic functional layer isa layer adhering to the co-extruded sheet or film as the protectivelayer or adhering to the polarizing functional layer.
 6. The functionalsheet according to claim 1, wherein the acrylic-based resin layer of theco-extruded sheet or film is a hard acrylic-based resin layer whichexhibits a pencil hardness of 2H or higher at a thickness of 60 μm, or asoft acrylic-based resin layer comprising, as a copolymerizationcomponent, 5 mol % or higher of alkyl(meth)acrylate having an alkylgroup with a carbon number of 2 or greater.
 7. The functional sheetaccording to claim 1, wherein the co-extruded sheet or film has aretardation of 3000 nm or greater.
 8. A lens obtained by a process bywhich the functional sheet according to claim 1 which comprises theacrylic-based resin layer at both surfaces thereof is subjected toexternal shape processing and subjected to bending processing whilebeing heated and pressurized.
 9. A molded lens obtained by a process bywhich the functional sheet according to claim 1, which comprises theacrylic-based resin layer at one surface and the aromatic polycarbonateresin layer at the other surface, is subjected to external shapeprocessing such that the acrylic-based resin layer is on a convexedsurface side, and is subjected to bending processing while being heatedand pressurized; then the resultant sheet is attached to a mold suchthat the convexed surface side is in contact with the mold; and anaromatic polycarbonate resin is provided on a concaved surface side ofthe sheet by injection molding.
 10. Sunglasses or goggles using the lensaccording to claim
 8. 11. Sunglasses or goggles using the lens accordingto claim 9.